The present invention relates generally to agricultural harvesters and, more specifically, to a speed control for such harvesters.
A self-propelled harvester such as a combine typically includes a header for engaging a crop. An automatic height control system utilizing a mechanical feeler or an acoustic sensor or similar non-contact ground sensing device maintains the header within a desired range of heights above the ground. The operator can also manually control the header to raise and lower the unit as necessary to compensate for different field conditions such as high or low yield conditions, irregular ground surface conditions, and downed crop conditions. In combines having a cutter bar which severs the crop below the crop heads and directs the severed crop to a central feeder house, changing the header height usually results in a significant change of the amount of material entering the feeder house. Lowering the header can immediately result in an increase in the material that will be input to the feeder house and processed by the harvester. Raising the header reduces the amount of material.
Various devices are available to sense the amount of material entering the feeder house or threshing and separating assembly and change the speed of the combine in response to changes in material to maintain a generally constant throughput, the delay in response time for such systems often results in an initial excessive amount of material in the feeder house, beater and threshing and separating assembly shortly after the header is quickly lowered for any reason. As a result of such header lowering, the combine becomes heavily loaded, increasing grain loss, power requirements and the potential for blockages, wear and premature component failure. Raising the header results in a short period of combine operation below capacity so that machine productivity is reduced
It is therefore an object of the present invention to provide an improved speed control system for a combine or other harvester having an adjustable header with a cutter bar. It is a further object to provide such a system which overcomes most or all of the aforementioned problems.
It is another object of the invention to provide such a harvester speed control system which reduces the problems associated with rapid variations in harvester throughput caused by header repositioning. It is another object to provide such a system that reduces or eliminates blockages and excessive loading, wear and grain loss caused by such repositioning. It is another object to provide such a system which reduces or eliminates lower machine productivity because of delays in response to throughput changes resulting from cut height changes.
It is yet another object of the invention to provide an improved harvester speed control system wherein harvester speed is quickly changed to compensate for the increase or decrease in throughput caused by a change in material volume that is a function of a cut height change. It is yet another object to provide such a system which is easily calibrated.
The system for improved harvester speed control includes a header position sensor such as a feeder house position transducer providing an indication of raising or lowering of the header. The output of the header position sensor is connected to a processor which estimates the change in volume of material that will have to be processed by the harvester as a result of a header height change. The volume change can be estimated by a simple calibration routine based on crop height. Volume change estimates are stored in the form of a table in processor memory and can be easily updated as necessary as crop conditions change. In another embodiment, automatic calibration based on cutting height changes and resulting feed rate changes using adaptive learning techniques is employed.
Combine speed adjustments are, normally controlled by a conventional speed control as a function of outputs of one or more sensors including a throughput sensor located downstream of the header. However, if the header is lowered, combine speed is immediately lowered to prevent a sudden increase in material downstream of the feeder housing input. The percentage speed reduction preferably is selected based upon estimated percentage increase in material for the given height change as determined during the calibration process. After a preselected delay, period wherein the material input to the header after the height change is processed downstream of the header, normal speed control based on throughput is resumed. If the header is raised, the speed of the combine is increased to maintain throughput.
These and other objects, features and advantages, of the present invention will become apparent to one skilled in the art upon reading the following detailed description in view of the drawings.